1. Technical Field
Exemplary aspects of the present invention generally relate to a lubricant applicator, an image forming apparatus including the lubricant applicator, and a process cartridge included in the image forming apparatus.
2. Related Art
Related-art image forming apparatuses, such as copiers, printers, facsimile machines, and multifunction devices having two or more of copying, printing, and facsimile capabilities, typically form a toner image on a recording medium (e.g., a sheet of paper, etc.) according to image data using, for example, an electrophotographic method. In the electrophotographic method, for example, a charger charges a surface of an image carrier (e.g., a photoconductor); an irradiating device emits a light beam onto the charged surface of the photoconductor to form an electrostatic latent image on the photoconductor according to the image data; a developing device develops the electrostatic latent image with a developer (e.g., toner) to form a toner image on the photoconductor; a transfer device transfers the toner image formed on the photoconductor onto a sheet of recording media; and a fixing device applies heat and pressure to the sheet bearing the toner image to fix the toner image onto the sheet. The sheet bearing the fixed toner image is then discharged from the image forming apparatus. The image forming apparatuses often further include a lubricant applicator that supplies a lubricant to a surface of an image carrier, such as the photoconductor and an intermediate transfer belt included in the transfer device, for protection and reduced friction.
However, when image formation is performed with the lubricant used up and not supplied to the image carrier, the image carrier, which is not protected by the lubricant, abrades and deteriorates. To solve this problem, the lubricant applicator often includes a lubricant detector that detects a stage in which the lubricant is almost used up (hereinafter referred to as a near-end stage of the lubricant).
FIG. 1 is a schematic perspective view illustrating an example of a configuration of a lubricant detector included in a related-art lubricant applicator.
The lubricant applicator illustrated in FIG. 1 includes a lubricant holder 143 formed of an electrically conductive material, a solid lubricant 140 held by the lubricant holder 143, and first and second electrode members 181 and 182 that contact both ends of the lubricant holder 143, respectively, when the solid lubricant 140 has a small amount remaining. A detection circuit 183 is connected to both the first and second electrode members 181 and 182, and applies a voltage between the first and second electrode members 181 and 182 to detect whether or not an electric current flows therebetween. The lubricant holder 143 is biased toward a supply member, not shown, by springs 142.
In the early stage of use of the solid lubricant 140, the lubricant holder 143 is positioned away and thus electrically isolated from both the first and second electrode members 181 and 182, so that no electric current flows between the first and second electrode members 181 and 182. As the solid lubricant 140 is gradually scraped off by the supply member over time, the lubricant holder 143 is moved toward the supply member by a biasing force of the springs 142. When the solid lubricant 140 reaches the near-end stage, the conductive lubricant holder 143 contacts the first and second electrode members 181 and 182. As a result, an electric current flows between the first and second electrode members 181 and 182, so that the detection circuit 183 detects the near-end stage of the solid lubricant 140.
However, as described above, the lubricant holder 143 contacts the first and second electrode members 181 and 182 when the solid lubricant 140 reaches the near-end stage, so that electrical continuity is established between the first and second electrode members 181 and 182. In other words, the lubricant holder 143 is positioned away and thus electrically isolated from both the first and second electrode members 181 and 182 from the early stage of use of the solid lubricant 140 until the near-end stage. Consequently, until the solid lubricant 140 reaches the near-end stage, powdered lubricant scraped off from the solid lubricant 140 may adhere to a contact portion in which the lubricant holder 143 and the first or second electrode member 181 or 182 contact each other. Adherence of the powdered lubricant to the contact portion hinders establishment of electrical continuity between the first and second electrode members 181 and 182 even when the lubricant holder 143 contacts the first and second electrode members 181 and 182, thereby possibly preventing detection of the near-end stage of the solid lubricant 140.